The state is gearing up for a $500,000 tweak to a brand new highway project in the metro area after finding that drivers don't know how to navigate it.

"Driver behavior is such a critical thing," said Sheila Kauppi, south metro area manager for the Minnesota Department of Transportation. "It's hard to model what needs to be done, because the human portion is hard to factor in. We do the best we can."

The problem is merging behavior during morning rush hour on an exceptionally busy stretch of road where Hwy. 13 in Scott County becomes Hwy. 101 and leads up to the Bloomington Ferry Bridge.

The state just completed a $19 million fix to the 13/101 junction, aimed at keeping traffic moving smoothly through an area where stoplights had created long lines of impatient motorists.

But as soon as it was in use, engineers noticed that long, needless tie-ups continued en route to the bridge.

"People have nearly a mile to do the merge they need to do to get over to the proper lane," Kauppi said. "But they try to do it immediately, where the dotted line starts to allow it. That causes congestion when cars are moving together and backs up the ramp, and it has a trickle-back effect."

Lezlie Vermillion, public works chief in Scott County, said the issues may stem in part from the novel nature of the fix the state applied. The new intersection involves an unusual partial-flyover bridge that takes some traffic up over the intersection and leaves some at ground level.

"This was new and innovative," she said, "and not that it doesn't work, but people don't merge correctly with it. They have about a mile to get over and they all want to do it in the first 300 feet. We have an education issue with that."

More lane space

The fix will involve adding more lane space as part of a $5.5 million project this year to maintain the Ferry Bridge, which is showing its age, engineers said.

The bigger picture, Kauppi stressed, is that the project has solved a lot of what was going wrong at the highly used intersection.

"It has addressed our main goal, which was intersection crashes," she said. "People were running red lights and having crashes. We've solved 90 percent of the issues we were having out there, and if we can now fix the merge as well, that would be awesome."